Jehan Bourgeois
architect.
One of the architects of the dukes of Burgundy. In 1387 he was employed on the portal of the Sainte Chapelle, at Dijon (Côte d'Or, France), under Jacques de Neuilly. December 9, 1404, he was made maître général of the ducal constructions, and from that time to 1417 worked on the fortifications of Dijon.

Marco Frisone (Frixono) (da Campione)
d. July 10, 1390.
Marco came to the works of the cathedral of Milan on March 5, 1387, the year after its commencement. Calvi supposes that he designed the building. This honour seems rather to belong to Simone da Orsenigo.

Andrea degli Organi (da Modena)
architect.
The first architect (ingegnere) employed on the cathedral of Milan (begun 1386). His name appears in a memorandum of January 15, 1387. April 13 he is mentioned as ingegnerio domini (ducal engineer). In October of this year he was appointed to superintend the labourers at the cathedral. In a letter dated January 3, 1400, of the Duke Gian Galeazzo Visconti, he is mentioned as the father of Filippino degli Organi.

Simone da Orsenigo
architect.
Simone came to the construction of the cathedral of Milan March 1, 1387. In a memorandum of October in the same year he is called inzignerio fabricae. He seems to have been the first supervising architect of the cathedral. It is possible that the building was designed by him.